So a few things to note... there are three separate water suppliers in Canfield, one is from the city which comes from Meander Resevoir, another is AQUA Ohio, and I can't recall the 3rd. You will notice there are multiple water towers in Canfield, the old one near Hilltop Elementary and SR-11 is for the city. There is a newer tower on the other side of SR-11 near Sheetz for AQUA.
There are no sewer lines running thay far South on SR-46, they stop way before the school. Had the school actually connected in to Canfield city water which is the only main running nearby as part of the process they would have been annexed as every property that is tied into Canfield water was annexed into Canfield if it wasn't already including a few housinv developments that are seemingly on islands.
From the attached screenshot from GIS it seems that some South Range property has a Beaver Township code and one each has 48 and 53 and I think one of those is Canfield and it gives an address as on Columbiana-Canfield Rd which is SR-46.
View attachment 36611
All this said, I think the property was never annexed because the school never tied into the water main from the city.